MODELING OF FLOW AND PARTICLE DYNAMICS HUMAN RESPIRATORY SYSTEM USING FLUID DYNAMICS

The aim of this research is to study numerically the flow characteristics and
particle transport within a human respiratory system, including the human nasal cavity
and the bifurcation. Various flow rates and particle sizes are main parameters varied
in order to analyze the effects on particle movements and deposition on the human
respiratory system. There are three main systems considered in this research: flow
around a blockage in a channel, flow in the Final particle deposition with Stokes
number, St = 0.12 for inlet flow rates of: (a) 30 L/min; (b) 60 L/min in human nasal
cavity, and flow in the double bifurcation. Computational Fluid Dynamics (CFD) is
used to solve gas-particle flow equations using a commercial software, FLUENT.
Flow around a blockage in a channel was performed to gain confidence in the
CFD model that has recirculation zone behind the block. The unsteady vortices flow
around this blockage is investigated for Reynolds numbers, Re = 150, 300, 600, 900,
and 1200 and Stokes numbers, St = 0.01, 0.1, 0.5, 1.0 and 2.0 by solving momentum
and particle model equations. A detailed airflow structures such as vortices, flow
distribution are obtained. It was found that the particle distribution depends on
vortical structures and Stokes number.
A model of real human nasal cavity is reconstructed from computerized
tomography (CT) scans. The flow structure is validated with experimental data for
flowrates of 7.5 L/min (Re = 1500) and 15 L/min (Re = 3000). The total particle
deposition in nasal cavity is also validated with experimental data using inertial
parameter. Then the model is further investigated the effect of turbulence on particle
deposition with flowrates of 20, 30 and 40 L/min. Deposition was found to increase
with Stoke number for the same Reynolds number.
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Three-dimensional double bifurcations with coplanar configurations are employed
to investigate the flow. Results of laminar flow (Re = 500, Re = 1036, and Re = 2000)
are used to compare with experimental and numerical solution for validation. The
model is further used to investigate the turbulent flow and particle deposition for
heavy breathing with flowrates of 30 L/min (Re = 7300) and 60 L/min (Re = 14600).
It was found that the deposition efficiency is dependent on Reynolds number and
Stokes numbers. This research outcome will guide to improve the injection particle
drugs to human lungs and to develop nasal mask to protect the lungs from hazardous
particles.